Over 400 species of fungi are known to live in the lawn habitat, but less than 25% are potentially harmful. Lawn diseases are caused primarily by fungi that live in the soil or thatch layer. Even the disease-causing fungi can live in association with the grass plants without damaging them as long as environmental conditions and cultural practices do not create opportunities for attack.
The disease-causing fungi can feed on decaying organic matter. They act as decomposers of dead plant parts such as lawn clippings and thatch, helping recycle plant nutrients. Other fungi that cause disease can remain in the soil for a long time in the inactive spore stage; they attack only when the lawn ecosystem is thrown out of balance by the various stresses, such as a high temperature combined with excessive irrigation and fertilization. That is where the fertilization hurts the lawn. It is the nitrogen that causes the problem when combined with lots of rain and humid nights. That is why we stress watering in the early morning instead of the late nights.
This suggests why good management, which involves proper irrigation, fertilization, and correct mowing are the best defense against lawn disease.
Now let’s step back and look at your lawn from a distance. First of all, check your irrigation timer. Have you set it for more than twice a week? With all the rain we have had, twice a week may even be too often. Second, do you have it set to come on before 2:00 am? Depending on how many zones you have, that may even be too early.
Third, does your lawn look like it is “melting away”? Is it yellowing or have a gray tint to it? Does the grass seem to be dying where the lawn mower tires went over the lawn?
If so, you may be going down the path to a fungi infested lawn. One way to test for a fungus in you lawn is to flip your fingers through the grass. If the grass blade breaks off at the node (elbow) and you have a brown spot at the break there is a good possibility you have a fungus. That is a weak point to the grass blade.
There are many different species of fungi, so finding and treating the correct one is important. You will probably have to contact a commercial company to find this out. At that point you will have to apply at least two applications to get it under control. Do not feed the problem. Solve the problem. You can also talk to your retail store and they will suggest the product to apply if you know the species of fungi.
Remember, fungi can always be present, however the right conditions can cause it to be a problem. So let’s solve the problem, and not feed the condition. Again, proper irrigation, fertilization and correct mowing is the right prescription for a healthy landscape.